The T'au Empire is the youngest of the major races currently at war in the galaxy.
Being highly advanced technologically for their age, the T'au operate on a policy of Greater Good, believing that the needs of the many outweigh the needs of the few. This carries forward into their battle strategies, with cooperation and teamwork being integral parts of their victories.
The T'au race is split into 5 castes; the Air Caste pilot ships and are taller and slimmer than other Tau; the Water Caste are diplomats; the Earth Caste builders and engineers; the Fire caste are stockier than their kin, and are the main fighting force of the Tau. The 5th caste are the elusive Ethereals, who command an almost mystical respect from amongst all the other castes, despite none of the T'au having any form of psychic ability.
As a young race the T'au don't have any form of faster than light travel, and their expansions into space have been done in what they refer to as 'Spheres'. Each Sphere expands their territory, and brings new races into the Greater Good, such as the Kroot and Vespid.
On the battlefields of Warhammer 40k, the T'au are masters of ranged warfare. Many of them wear imposing and impressive battlesuits, allowing them to bring more heavy weaponry to bear. Being physically weaker than most other races, they do well to stay out of melee, but more than make up for their weaknesses with devastating amounts of firepower. This makes them a good army for those newer to the game, as there are few things to worry about outside of getting in position to take shots!
From a painting perspective the T'au offer options for a mixture of colour schemes, but look good in bright colours with their battlesuits having plenty of opportunity for panel lining and edge highlighting.